A Comparison of the Growth of Mice which Ultimately Develop Carcinoma with the Growth of Mice which do not Develop Carcinoma

Abstract

Since cancer is a disease of growth, and its incidence in appreciable form is usually deferred until after the attainment of maturity, a very important factor in our ultimate understanding of the etiology of cancer must arise out of a knowledge of the degree to which the preceding development of the animal is affected by the ultimate aberration of growth. If the factors which determine the growth and incidence of carcinoma, for example, are of an essentially accidental character, such as local irritation plus infection, then the incidence of carcinoma in an individual will be decided in the main by factors not inherent in its habit of growth and metabolism, and the preceding normal development cannot be expected to foreshadow the impending pathological outcome. If, on the contrary, the incidence of carcinoma is determined by internal factors of growth-habit or metabolic peculiarities plus recurrent external factors, such as local irritation, then the underlying peculiarity of growth or metabolism may conceivably reveal itself in more or less marked departures from the average in the preceding normal development. A comparison throughout the duration of life of the growth of animals which ultimately develop spontaneous cancer and those which do not is, therefore, fundamental to our comprehension of the etiology of this disease. The fact that such a comparison has not hitherto been instituted is undoubtedly attributable to the experimental labor which is essential to obtain results of any worth, to the expenditure of time which is requisite, and to the difficulty of an experimental technique which must obviously be devised to exclude all chance causes of death, among which must be reckoned epidemic infections. It is obvious that if epidemic infections were from time to time to claim a substantial proportion of victims among the experimental animals, it would become impossible to identify the individuals which, had they survived the infection, would subsequently have developed carcinoma.